The present invention relates to a suction system for an internal combustion engine with a device for avoiding the ingress of water.
In general, the ingress of water via a suction system is undesired in internal combustion engines. Because the internal combustion engine is supposed to be supplied with outside air, however, there is always the risk that water will reach the intake port. Of course, intake of air from the engine compartment significantly reduces the risk of an ingress of water, but leads simultaneously to a higher air temperature in the engine compartment. This has the drawback of a decrease in the performance of the internal combustion engine performance, an effect that is very disturbing at high driving speeds.
DE 37 36 777 C1 has already disclosed a device for avoiding the ingress of water into an air filter housing, disposed in a fresh air intake line in an internal combustion engine. In this device the ingress of water is detected by a water sensor in the fresh air intake line. A control unit reverses a switch-over valve disposed downstream of the water sensor in the fresh air intake line. Thereby, at this stage the internal combustion engine is connected to an engine compartment intake line. As soon as the water sensor no longer perceives any water, the switch-over valve is reset, and in so doing the internal combustion engine is supplied from the fresh air intake line. For this known device to function, however, water must have already penetrated into the intake line, so that the intake path may be switched over, and the internal combustion engine is protected against the ingress of water.
An object of the invention is to provide a suction system with improved protection against the ingress of water. This protection shall be effective even if, for example, the fresh air intake line is totally covered with water, as is possible, for example, when wading through a body of water.
This object has been achieved by actuating a switch-over valve during off-road travel. That is, the switch-over valve is controlled so that, during off-road travel, a change-over occurs from a primary air intake to a secondary air intake.
According to the present invention, off-road travel is detected when a switch that is provided for operating the transmission is actuated for selecting an off-road reduction group. As an alternative (or in addition), the position of a switch may also be used to increase the ground clearance of the vehicle.
The primary intake line is preferably a fresh air intake line, i.e., an intake line, whose intake port is located outside of the vehicle. The secondary intake line is preferably configured as an engine compartment intake line whose intake port is located in a water-protected spot and in a manner that it lies as high geodetically as possible. It may, for example, be an intake line in the engine compartment. In that case, this intake port must take in air that is as cool as possible. Other locations of the intake port are also contemplated, however, such as a snorkel projecting beyond the vehicle, as long as locations are protected against the ingress of water.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.